Fungicidal trihalophenyl-triazolopyrimidines

ABSTRACT

The novel compounds of formula I:                    
     (R 1  to R 5  and X are defined in the specification) show selective fungicidal activity, in particular against rice blast disease. The new compounds are processed with carriers and, optionally, an adjuvant to provide fungicidal compositions.

This is a continuation-in-part of application Ser. No. 09/160,568 filed on Sep. 25, 1998 now U.S. Pat. No. 5,985,883, and claims benefit of Provisional No. 60/101,764, filed Sep. 25, 1998 the entire disclosure of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

This invention relates to certain triazolopyrimidine compounds, a process for their preparation, compositions containing such compounds, a method for combating a fungus at a locus comprising treating the locus with such compounds and their use as fungicides.

EP-A-0071792 claims compounds of the general formula

in which R¹ represents alkyl, halogen, alkoxy, cyano, cycloalkyl, aryl, aryloxy, arylthio, aralkyl, arylthio, arylalkyl, arylalkyloxy or arylalkylthio each optionally substituted by halogen or alkoxy; or (R¹)_(n) represents a benzene, indane or tetrahydronaphthalene ring fused with the phenyl ring, aromatic moieties in the above groups being optionally substituted by alkyl, alkoxy, halogen or cyano; n is 1 or 2; R² and R³ are each hydrogen, alkyl or aryl, A represents a nitrogen atom or a CR⁴ group, and R⁴ is as R² but can also be halogen, cyano or alkoxycarbonyl or together with R³ can form an alkylene chain containing up to two double bonds. The compounds are said to be active against various phytopathogenic fungi, especially those of the phycomycete class. However evidence of fungicidal activity is only provided for these compounds against Plasmopara viticola, a member of the oomycete class of fungi.

U.S. Pat. No. 5,593,996 embraces compounds of the general formula 1

in which R¹ represents an optionally substituted alkyl, alkenyl, alkadienyl, cycloalkyl, bicycloalkyl or heterocyclyl group; R² represents a hydrogen atom or an alkyl group; or R¹ and R² together with the interjacent nitrogen atom represent an optionally substituted heterocyclic ring; R³ represents an optionally substituted aryl group; and R⁴ represents a hydrogen or halogen atom or a group —NR⁵R⁶ where R⁵ represents a hydrogen atom or an amino, alkyl, cycloalkyl or bicycloalkyl group and R⁶ represents a hydrogen atom or an alkyl group. Thus, compounds in which R³ is a trichlorophenyl group are generally covered by this patent application. These compounds are said to be active against fungi which are members of the ascomycetes class such as Venturia inaequalis and of the hyphomycetes class such as Alternaria solani and Botrytis cinerea. However, there is no single compound disclosed in which R³ is a phenyl group, trisubstituted in the 2,4,6-positions by fluorine and/or chlorine atoms.

SUMMARY OF THE INVENTION

The present invention provides a compound of formula I

in which

R¹ and R² each independently represent a hydrogen atom or an optionally substituted alkyl, alkenyl, alkynyl, alkadienyl, haloalkyl, aryl, heteroaryl, cycloalkyl, bicycloalkyl or heterocyclyl group, or

R¹ and R² together with the interjacent nitrogen atom represent an optionally substituted heterocyclic ring;

R³, R⁴ and R⁵ each independently represent a fluorine or a chlorine atom, provided that at least one of R³, R⁴ and R⁵ is a chlorine atom.

X represents a halogen atom.

The new compounds show an excellent fungicidal activity in various crops, in particular against Pyricularia oryzae (Magnaporthe grisea) the causative agent of rice blast disease.

It is an object of the present invention to provide novel, selective fungicidal compounds.

It is also an object of the invention to provide methods for controlling an undesired fungus, in particular Pyricularia oryzae the causative agent of rice blast disease, by contacting said plants with a fungicidally effective amount of the new compounds.

It is another object of the invention to provide fungicidal compositions containing the new compounds as active ingredients.

These and other objects and features of the invention will be more apparent from the detailed description set forth hereinbelow, and from the appended claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

It has surprisingly been found that the compounds of formula I

in which R¹ to R⁵ and X have the meaning given above for formula I show excellent fungicidal activity against a broad range of fungi, in particular against Pyricularia oryzae, the causative agent of rice blast disease.

As used herein, the term halogen atom includes a bromine, iodine, chlorine or fluorine atom, and especially a bromine, chlorine or fluorine atom, in particular a chlorine atom.

Optionally substituted moieties may be unsubstituted or have from one up to the maximal possible number of substituents. Typically, 0 to 2 substituents are present. The term ‘optionally substituted’, as used herein with reference to a group, means that the group is substituted by one or more halogen atoms, or by nitro, cyano, hydroxy, alkyl (preferably C₁₋₆ alkyl), cycloalkyl (preferably C₃₋₆ cycloalkyl), cycloalkenyl (preferably C₃₋₆ cycloalkenyl), haloalkyl (preferably C₁₋₆ haloalkyl), halocycloalkyl (preferably C₃₋₆ halocycloalkyl), alkoxy (preferably C₁₋₆ alkoxy), haloalkoxy (preferably C₁₋₆ haloalkoxy), trialkylsilyl (preferably tri-C₁₋₄ alkylsilyl), phenyl, halo- or dihalo-phenyl or pyridyl groups.

The terms alkyl, alkenyl, alkynyl, alkadienyl, haloalkyl as used herein with respect to a radical or moiety refer to a straight or branched chain radical or moiety. Preferably, such radicals or moieties have up to 10, in particular up to 6, carbon atoms. Suitably, an alkyl moiety has from 1 to 6 carbon atoms, preferably from 1 to 4 carbon atoms. A preferred alkyl moiety is an ethyl or, especially, a methyl group. Suitably, an alkenyl moiety has from 2 to 6 carbon atoms. A preferred alkenyl moiety is allyl or, especially, a 2-methylallyl group. Suitably, a haloalkyl moiety has from 1 to 6 fluoro atoms. Preferred haloalkyl moieties includes the 2,2,2-trifluoroethyl and 1,1,1-trifluoroprop-2-yl groups.

The term aryl, as used herein with respect to a radical or moiety, refers to an aryl group having 6, 10 or 14 carbon atoms, preferably 6 or 10 carbon atoms, in particular phenyl optionally substituted by one or more halogen atoms, nitro, cyano, alkyl, preferably C₁₋₆ alkyl, and/or alkoxy, preferably C₁₋₆ alkoxy.

The term heteroaryl, as used herein with respect to a radical or moiety, refers to a heteroaryl group having 5 or 6 ring atoms selected from carbon, nitrogen, oxygen and sulphur, at least one of which is nitrogen, oxygen or sulphur, in particular pyridyl, pyrimidyl, pyrazolyl or thienyl.

The term cycloalkyl, as used herein with respect to a radical or moiety, refers to a cycloalkyl group having 3 to 8 carbon atoms, preferably 5 to 7 carbon atoms, in particular cyclopentyl optionally substituted by one or more halogen atoms, nitro, cyano, alkyl, preferably C₁₋₆ alkyl, and/or alkoxy, preferably C₁₋₆ alkoxy.

The term bicycloalkyl, as used herein with respect to a radical or moiety, refers to a bicycloalkyl group having 5 to 10 carbon atoms, preferably 6 to 9 carbon atoms, in particular bicycloheptyl optionally substituted by one or more halogen atoms, nitro, cyano, alkyl, preferably C₁₋₆ alkyl, and/or alkoxy, preferably C₁₋₆ alkoxy.

The term heterocyclyl, as used herein with respect to a radical or moiety, refers to a saturated heterocyclyl group having 5 or 6 ring atoms selected from carbon, nitrogen, oxygen and sulphur, at least one of which is nitrogen, oxygen or sulphur, optionally substituted by one or more halogen atoms, nitro, cyano, alkyl, preferably C₁₋₆ alkyl, and/or alkoxy, preferably C₁₋₆ alkoxy. Pyrrolodinyl, pyrrazolidinyl, piperidinyl, piperazinyl and morpholin-4-yl are particularly preferred.

The invention especially relates to compounds of formula I in which any alkyl or haloalkyl part of the groups R¹ or R², which may be straight chained or branched, contains up to 10 carbon atoms, preferably 1 to 9 carbon atoms, and more preferably 2 to 6 carbon atoms, any alkenyl or alkynyl part of the substituents R¹ or R² contains up to 10 carbon atoms, preferably 2 to 9 carbon atoms, and more preferably 3 to 6 carbon atoms, any cycloalkyl part of the substituents R¹ or R² contains from 3 to 10 carbon atoms, preferably from 3 to 8 carbon atoms, more preferably from 3 to 6 carbon atoms, any bicycloalkyl part of the substituents R¹ or R² contains from 5 to 9 carbon atoms, preferably from 7 to 9 carbon atoms, and any aryl part of the substituent R¹ or R² contains 6, 10 or 14 carbon atoms, preferably 6 or 10 carbon atoms.

In a preferred embodiment, the invention includes compounds of formula I in which R¹ represents a straight-chained or branched C₁₋₁₀ alkyl (in particular a branched C₃₋₁₀ alkyl group), a C₃₋₈ cycloalkyl, a C₅₋₉ bicycloalkyl, a C₃₋₈ cycloalkyl-C₁₋₆ alkyl, C₁₋₁₀ alkoxy-C₁₋₆ alkyl, a C₁₋₁₀ haloalkyl or a phenyl group optionally substituted by one to three halogen atoms or C₁₋₁₀ alkyl or C₁₋₁₀ alkoxy groups.

Also preferred are compounds of formula I in which R² represents a hydrogen atom, a C₁₋₁₀ alkyl or a C₁₋₁₀ haloalkyl group, in particular a hydrogen atom.

When R¹ denotes a C₁₋₁₀ haloalkyl group, preferably a polyfluorinated alkyl group, in particular a 2,2,2-trifluoroethyl, a 2-(1,1,1-trifluoropropyl) or a 2-(1,1,1-trifluorobutyl) group, R² preferably represents a hydrogen atom.

When R¹ denotes an optionally substituted C₃₋₈ cycloalkyl group, preferably a cyclopentyl or cyclohexyl group, R² preferably represents a hydrogen atom or C₁₋₆ alkyl group.

In another preferred embodiment of the invention, R¹ and R² together with the interjacent nitrogen atom form an optionally substituted heterocyclic ring, preferably an optionally substituted C₃₋₇ heterocyclic ring, in particular a pyrrolidine, piperidine, tetrahydropyridine, in particular 1,2,3,6-tetrahydropyridine or azepane ring which is optionally substituted by one or more C₁₋₁₀ alkyl groups, most preferably 4-methylpiperidine.

The invention especially relates to compounds of formula I in which: R³, R⁴ and R⁵ are chlorine atoms; R³ is a chlorine atom, R⁴ is a fluorine atom, and R⁵ is a fluorine or a chlorine atom, preferably where R⁵ represents a chlorine atom; or, R³ and R⁴ are fluorine atoms and R⁵ is a chlorine atom.

Accordingly, in formula I the phenyl group

preferably represents a group selected from

Included in the scope of the present invention are (R) and (S) isomers of compounds of formula I having a chiral center and the racemates thereof, and salts, N-oxides and acid addition compounds.

The compounds according to formula I may be oils, gums, or waxy or crystalline solid materials. They exhibit valuable fungicidal properties, such as enhanced systemicity and enhanced fungicitoxity against rice diseases and powdery mildews compared to known fungicides. For example, they can be used in agriculture or related fields for the control of phytopathogenic fungi such as Alternaria solani, Botrytis cinerea, Cercospora beticola, Cladosporium herbarum, Corticium rolfsii, Erysiphe graminis, Helminthosporium tritici repentis, Leptosphaeria nodorum, Micronectriella nivalis, Monilinia fructigena, Mycosphaerella ligulicola, Mycosphaerella pinodes, Pyricularia oryzae, Rhizoctonia solani and Sclerotinia sclerotiorum, Uncinula necator, in particular for the control of Pyricularia oryzae. The compounds of formula I according to the invention possess a high fungicidal activity within a wide concentration range and may be used in agriculture without any difficulties.

Moreover, the compounds according to the invention show enhanced control of fungi, in particular of rice blast disease compared with conventional fungicides.

Good results in terms of control of phytopathogenic fungi are obtained with a compound as defined in formula I wherein:

X represents a chloro atom,

R² represents a hydrogen atom,

R³ and R⁵ represent chlorine atoms, and

R⁴ represents a chlorine or fluorine atom.

Especially good results in terms of control of phytopathogenic fungi are obtained by using, for example, the following compounds of formula I:

[5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-cyclopentyl-amine;

[5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-7-(4-methyl-piperidin-1-yl)-1,2,4]triazolo[1,5α]pyrimidine;

[5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-(2,2,2-trifluoro-ethyl)-amine;

[5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-(1,1,1-trifluoro-prop-2-yl)-amine;

[5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-diethyl-amine;

[5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-isopropyl-amine;

sec-Butyl-[5-chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-amine;

Bicyclo[2.2.1]hept-2-yl-[5-chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-amine;

[5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-cyclopentyl-amine;

[5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-7-(4-methyl-piperidin-1-yl)-1,2,4]triazolo[1,5-α]pyrimidine;

[5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-(2,2,2-trifluoroethyl)-amine;

[5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-(1,1,1-trifluoro-prop-2-yl)-amine;

[5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-diethyl-amine;

[5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-isopropyl-amine;

sec-Butyl-[5-chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-amine;

Bicyclo[2.2.1]hept-2-yl-[5-chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-amine;

but-2-yl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amine;

isopropyl-[5-chloro-6(2,4,6-trichlorophenyl-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amine;

[5-chloro-6-(2,4,6-trichloro-phenyl)-7-(3-methyl-piperidin-1-yl)-1,2,4]triazolo[1,5-α]pyrimidine;

cyclopentyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7yl]-amine;

5-chloro-6-(2,4,6-trichloro-phenyl)-7-(4-methyl-piperidin-1-yl)-[1,2,4]triazolo[1,5α]pyrimidine;

diethyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amine;

norborn-2-yl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]-pyrimidin-7-yl]amine;

cyclopropyl-[5-chloro-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amine;

2,2,2-trifluoroethyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]-pyrimidin-7-yl-amine;

N-ethyl-N-2-methylallyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo [1,5-a]pyrimidin-7-yl]-amine; and,

1,1,1-trifluoroprop-2-yl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo [1,5-a]pyrimidin-7-yl]-amino.

The present invention further provides a process for the preparation of a compound of formula I as defined above which comprises treating a compound of the formula II

in which

R³, R⁴, R⁵ and X are as defined for formula I;

with an amine of formula III

in which

R¹ and R² are as defined for formula I.

Compounds of formula II are novel and can be prepared by reacting 3-amino-1,2,4-triazole with 2-(2,4,6-trihalophenyl)-substituted malonic acid ester of formula IV,

wherein R³, R⁴ and R⁵ are as defined for formula I, R represents alkyl, preferably C₁₋₆ alkyl, in particular methyl or ethyl, under alkaline conditions, preferably using high boiling tertiary amines, for example tri-n-butylamine.

The resulting 5,7-dihydroxy-6-(2,4,6-trihalophenyl)triazolopyrimidine is subsequently treated with a halogenating agent, preferably with a brominating or chlorinating agent, such as phosphorus oxybromide or phosphorus oxychloride, neat or in the presence of a solvent. The reaction is suitably carried out at a temperature in the range from 0° C. to 150° C., the preferred reaction temperature being from 80° C. to 125° C.

The compounds of formula IV are preferably prepared by reaction of 2,4,6-trihalobromobenzene with sodium dialkylmalonates in the presence of a copper(I) salt, e.g. as taught by J. Setsume et al. Chemistry Letters, pp. 367-370, 1981.

Accordingly, the invention relates to the novel intermediates of formula II, in particular 5,7-dichloro-6-(2,4,6-trichloro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidine, 5,7-dichloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidine and 5,7-dichloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidine, to the corresponding dialkyl-(2,4,6-trihalophenyl)-malonates of formula IV; and to the corresponding 5,7-dihydroxy-6-(2,4,6-trihalophenyl)-[1,2,4]triazolo [1,5-α]pyrimidines.

The reaction between the 5,7-dihalo-6-(2,4,6-trihalophenyl)triazolopyrimidines of formula II and the amine of formula III is preferably carried out in the presence of a solvent. Suitable solvents include ethers, such as dioxane, diethyl ether and, especially, tetrahydrofuran, halogenated hydrocarbons such as dichloromethane and aromatic hydrocarbons, for example toluene. The reaction is suitably carried out at a temperature in the approximate range from 0° C. to 70° C., the preferred reaction temperature being from 10° C. to 35° C. It is also preferred that the reaction is carried out in the presence of a base. Suitable bases include tertiary amines, such as triethylamine, and inorganic bases, such as potassium carbonate or sodium carbonate. Alternatively, an excess of the compound of formula III may serve as a base.

Due to excellent activity, the compounds of formula I may be used in cultivation of all plants where infection by phytopathogenic fungi is not desired, e.g. cereals, solanaceous crops, vegetables, legumes, apples, vine.

The invention further provides a fungicidal composition which comprises an active ingredient, which is at least one compound of formula I as defined above, and one or more carriers. A method of making such a composition is also provided which comprises bringing a compound of formula I into association with the carrier(s). Such a composition may contain a single active ingredient or a mixture of several active ingredients of the present invention. It is also envisaged that different isomers or mixtures of isomers may have different levels or spectra of activity and thus compositions may comprise individual isomers or mixtures of isomers.

A composition according to the invention preferably contains from 0.5% to 95% by weight (w/w) of active ingredient.

A carrier in a composition according to the invention is any material with which the active ingredient may be formulated to facilitate application to the locus to be treated (which may for example be a plant, seed, soil, or water in which a plant grows), or to facilitate storage, transport or handling. A carrier may be a solid or a liquid, including material which is normally a gas but which has been compressed to form a liquid.

The compositions may be manufactured into, e.g., emulsion or emulsifiable concentrates, solutions, oil in water emulsions, wettable powders, soluble powders, suspension concentrates, dusts, granules, water dispersible granules, aerosols, microcapsules, gels, tablets and other formulation types by well-established procedures. These procedures may include intensive mixing and/or milling of the active ingredients with other substances, such as fillers, solvents, solid carriers, surface active compounds (surfactants), and optionally solid and/or liquid auxiliaries and/or adjuvants. The form of application, such as spraying, atomizing, dispersing or pouring, may be chosen, like the compositions, according to the desired objectives and the given circumstances.

Solvents suitable in the practice of this invention include aromatic hydrocarbons, e.g. Solvesso® 200, substituted naphthalenes, phthalic acid esters, such as dibutyl or dioctyl phthalate, aliphatic hydrocarbons, e.g. cyclohexane or paraffins, alcohols and glycols as well as their ethers and esters, e.g. ethanol, ethyleneglycol mono- and dimethyl ether, ketones such as cyclohexanone, strongly polar solvents such as N-methyl-2-pyrrolidone, or γ-butyrolactone, higher alkyl pyrrolidones, e.g. n-octylpyrrolidone or cyclohexylpyrrolidone, epoxidized plant oil esters, e.g. methylated coconut or soybean oil ester and water. Mixtures of different solvents are often suitable.

Solid carriers, which may be used for dusts, wettable powders, water dispersible granules, or granules, may be mineral fillers, such as calcite, talc, kaolin, montmorillonite or attapulgite. The physical properties may be improved by addition of highly dispersed silica gel or polymers. Carriers for granules may be porous material, e.g. pumice, kaolin, sepiolite, bentonite; non-sorptive carriers may be calcite or sand. Additionally, a multitude of pre-granulated inorganic or organic materials may be used, such as dolomite or crushed plant residues.

Pesticidal compositions are often formulated and transported in a concentrated form which is subsequently diluted by the user before application. The presence of small amounts of a carrier which is a surfactant facilitates this process of dilution. Thus, preferably at least one carrier in a composition according to the invention is a surfactant. For example, the composition may contain at two or more carriers, at least one of which is a surfactant.

Surfactants may be nonionic, anionic, cationic or zwitterionic substances, preferably with good dispersing, emulsifying and wetting properties, which will depend on the nature of the compound according to formula I to be formulated. Surfactants may also include mixtures of individual surfactants.

Wettable powders of this invention suitably contain about 5 to 90% w/w of active ingredient and, in addition to solid inert carrier, about 3 to 10% w/w of dispersing and wetting agents and, about 0 to 10% w/w of stabilizer(s) and/or other additives such as penetrants or stickers. Dusts may be formulated as a dust concentrate having a similar composition to that of a wettable powder, but without a dispersant, and may be diluted in the field with further solid carrier to make a composition containing about 0.5 to 10% w/w of active ingredient. Water dispersible granules and granules suitably have a size approximately between 0.15 mm and 2.0 mm and may be manufactured by a variety of techniques known in the art. Generally, these granules will contain about 0.5 to 90% w/w active ingredient and about 0 to 20% w/w of additives such as stabilizer, surfactants, slow release modifiers and binding agents. Emulsifiable concentrates of this invention suitably contain, in addition to a solvent or a mixture of solvents, about 1 to 80% w/v active ingredient, about 2 to 20% w/v emulsifiers and about 0 to 20% w/v of other additives such as stabilizers, penetrants and corrosion inhibitors. Suspension concentrates may be milled to obtain a stable, non-sedimenting flowable product, and preferably contain about 5 to 75% w/v active ingredient, about 0.5 to 15% w/v of dispersing agents, about 0.1 to 10% w/v of suspending agents such as protective colloids and thixotropic agents, about 0 to 10% w/v of other additives such as defoamers, corrosion inhibitors, stabilizers, penetrants and stickers, and water or an organic liquid in which the active ingredient is substantially insoluble; certain organic solids or inorganic salts may be present dissolved in the formulation to assist in preventing sedimentation and crystalization or as antifreeze agents.

Aqueous dispersions and emulsions, for example compositions obtained by diluting the formulated product according to the invention with water, also lie within the scope of the invention.

The duration of the protective activity of the compounds of this invention may be enhanced by using a carrier which will provide slow release of the pesticidal compounds into the environment of a plant which is to be protected.

The biological activity of the active ingredient may also be increased by including an adjuvant in a spray dilution thereof. An adjuvant is defined here as a substance which can increase the biological activity of an active ingredient but is not itself significantly biologically active. The adjuvant can either be included in the formulation as a coformulant or carrier, or can be added to the spray tank together with the formulation containing the active ingredient.

As a commodity, the compositions preferably may be in a concentrated form, whereas the end user generally employs diluted compositions. The compositions may be diluted to a concentration down to about 0.001% of active ingredient, preferably in the approximate range from 0.01 to 10 kg a.i./ha.

Examples of formulations according to the invention are:

Emulsion Concentrate (EC) Active ingredient Compound of Example 5 30% (w/v) Emulsifier(s) Atlox ® 4856 B/Atlox ® 4858 B¹⁾ 5% (w/v) (mixture containing calcium alkyl aryl sulfonate, fatty alcohol ethoxylates and light aromatics/mixture containing calcium alkyl aryl sulfonate, fatty alcohol ethoxylates and light aromatics) Solvent Shellsol ® A²⁾ to 1000 ml (mixture of C₉-C₁₀ aromatic hydrocarbons) Suspension Concentrate (SC) Active Ingredient Compound of Example 5 50% (w/v) Dispersing agent Soprophor ® FL³⁾ 3% (w/v) (polyoxyethylene polyaryl phenyl ether phosphate amine salt) Antifoaming agent Rhodorsil ® 422³⁾ 0.2% (w/v) (nonionic aqueous emulsion of polydimethylsiloxanes) Structure agent Kelzan ® S⁴⁾ 0.2% (w/v) (Xanthan gum) Antifreezing agent Propylene glycol 5% (w/v) Biocidal agent Proxel ®⁵⁾ 0.1% (w/v) (aqueous dipropylene glycol solution containing 20% 1,2-benisothiazolin-3-one) Water to 1000 ml Wettable Powder (WP) Active Ingredient Compound of Example 11 60% (w/w) Wetting agent Atlox ® 4995¹⁾ 2% (w/w) (polyoxyethylene alkyl ether) Dispersing agent Witcosperse ® D-60⁶⁾ 3% (w/w) (mixture of sodium salts of condensed naphthalene sulfonic acid and alkylarylpolyoxy acetates Carrier/Filler Kaolin 35% (w/w) Water Dispersible Granules (WG) Active Ingredient Compound of Example 11 50% (w/w) Dispersing/ Witcosperse ® D-450⁶⁾ 8% (w/w) Binding agent (mixture of sodium salts of condensed naphthalene sulfonic acid and alkyl sulfonates) Wetting agent Morwet ® EFW⁶⁾ 2% (w/w) (formaldehyde condensation product) Antifoaming Rhodorsil ® EP 6703³⁾ 1% (w/w) agent (encapsulated silicone) Disintegrant Agrimer ® ATF⁷⁾ 2% (w/w) (cross-linked homopolymer of N-vinyl-2- pyrrolidone) Carrier/Filler Kaolin 35% (w/w) ¹⁾commercially available from ICI Surfactants ²⁾commercially available from Deutsche Shell AG ³⁾commercially available from Rhône-Poulenc ⁴⁾commercially available from Kelco Co. ⁵⁾commercially available from Zeneca ⁶⁾commercially available from Witco ⁷⁾commercially available from International Speciality Products

The compositions of this invention can be applied to plants or their environment, either simultaneously with or in succession with other active substances. These other active substances can be either fertilizers, agents which donate trace elements, or other preparations which influence plant growth. They can also be selective herbicides, insecticides, fungicides, bactericides, nematicides, algicides, molluscicides, rodenticides, virucides, compounds inducing resistance into plants, biological control agents such as viruses, bacteria, nematodes, fungi and other microorganisms, repellents of birds and animals, and plant growth regulators, or mixtures of several of these preparations, if appropriate together with other carrier substances conventionally used in the art of formulation, surfactants or other additives which promote application.

Furthermore, the other pesticide may have a synergistic effect on the pesticidal activity of the compound of formula I.

The other fungicidal compound may be, for example, one which is also capable of combating diseases of cereals (e.g. wheat) such as those caused by Erysipha, Puccinia, Septoria, Gibberella and Helminthosporium spp., seed and soil borne diseases and downy and powdery mildews on vines, early and late blight on solanaceous crops, and powdery mildew and scab on apples etc. These mixtures of fungicides may have a broader spectrum of activity than the compound of formula I alone. Furthermore, the other fungicide may have a synergistic effect on the fungicidal activities of the compound of formula I.

Examples of the other fungicidal compounds are AC 382042, alanycarb, aldimorph, ampropylfos, andoprim, anilazine, azaconazole, azafenidin, azoxystrobin, benalaxyl, benomyl, bethoxazin, binapacryl, bitertanol, blasticidin S, Bordeaux mixture, bromuconazole, bupirimate, captafol, captan, carbendazim, carboxin, carpropamid, chlorbenzthiazon, chlorothalonil, chlozolinate, copper-containing compounds such as copper oxychloride, and copper sulfate, cycloheximide, cymoxanil, cypofuram, cyproconazole, cyprodinil, dichlofluanid, dichlone, dichloran, diclobutrazol, diclocymet, diclomezine, diethofencarb, difenoconazole, diflumetorim, dimethirimol, dimethomorph, diniconazole, dinocap, ditalimfos, dithianon, dodemorph, dodine, edifenphos, epoxiconazole, etaconazole, ethaboxam, ethirimol, etridiazole, famoxadone, fenanidone, fenapanil, fenarimol, fenbuconazole, fenfuram, fenhexamid, fenpiclonil, fenpropidin, fenpropimorph, fentin, fentin acetate, fentin hydroxide, ferimzone, fluazinam, fludioxonil, flumetover, fluquinconazole, flusilazole, flusulfamide, flutolanil, flutriafol, folpet, fosetyl-aluminium, fuberidazole, furalaxyl, furametpyr, guazatine, hexaconazole, imazalil, iminoctadine, ipconazole, iprodione, iprovalicarb, ISK-916, isoprothiolane, kasugamycin, kitazin P, kresoxim-methyl, mancozeb, maneb, mepanipyrim, mepronil, metalaxyl, metconazole, methfuroxam, myclobutanil, neoasozin, nickel dimethyldithiocarbamate, nitrothalisopropyl, nuarimol, ofurace, organo mercury compounds, oxadixyl, oxpoconazole, oxycarboxin, penconazole, pencycuron, phenazineoxide, phthalide, picoxystrobin, polyoxin D, polyram, probenazole, prochloraz, procymidione, propamocarb, propiconazole, propineb, pyrazophos, pyrifenox, pyrimethanil, pyroquilon, pyroxyfur, quinomethionate, quinoxyfen, quintozene, RH-7281, (MON-65500), spiroxamine, SSF-126, SSF-129, streptomycin, sulfur, tebuconazole, tecloftalame, tecnazene, tetraconazole, thiabendazole, thifluzamide, thiophanate-methyl, thiram, tolclofosmethyl, tolylfluanid, triadimefon, triadimenol, triazbutil, triazoxide, tricyclazole, tridemorph, trifloxystrobin, triflumizole, triforine, triticonazole, validamycin A, vinclozolin, XRD-563, zarilamid, zineb, and ziram.

In addition, the co-formulations according to the invention may contain at least one compound of formula I and any of the following classes of biological control agents such as viruses, bacteria, nematodes, fungi, and other microorganisms which are suitable to control insects, weeds or plant diseases or to induce host resistance in the plants. Examples of such biological control agents are: Bacillus thuringiensis, Verticillium lecanii, Autographica californica NPV, Beauvaria bassiana, Ampelomyces quisqualis, Bacilis subtilis, Pseudomonas chlororaphis, Pseudomonas fluorescens, Steptomyces griseoviridis and Trichoderma harzianum.

Moreover, the formulations according to the invention may contain at least one compound of formula I and a chemical agent that induces the systemic acquired resistance in plants, such as isonicotinic acid, or derivatives thereof, 2,2-dichloro-3,3-dimethylcyclopropylcarboxylic acid or BION.

The compounds of formula I may be mixed with soil, peat or other rooting media for the protection of the plants against seed-borne, soil-borne or foliar fungal diseases.

The invention still further provides the use as a fungicide of a compound of the formula I, or a composition as defined above, and a method for combating fungus at a locus (which comprises treating the locus, which may be for example plants subject to or subjected to fungal attack, seeds of such plants or the medium in which such plants are growing or are to be grown), with such a compound or composition.

The present invention is of wide applicability in the protection of crop and ornamental plants against fungal attack. Typical crops which may be protected include vines, grain crops such as wheat and barley, rice, sugar beet, top fruit, peanuts, potatoes, vegetables and tomatoes. The duration of the protection is normally dependent on the individual compound selected, and also a variety of external factors, such as climate, the impact of which may be mitigated by the use of a suitable formulation.

The following examples further illustrate the present invention. It should be understood, however, that the invention is not limited solely to the particular examples given below.

EXAMPLE 1 Preparation of 1-Bromo-2,6-dichloro-4-fluoro-benzene

Bromine (0.6 mol) is added to a mixture of 1,3-dichloro-5-fluorobenzene (0.6 mol) and ferrous powder within 2 hours. The brown reaction mixture is stirred 16 hours at room temperature and subsequently washed with dichloromethane and water. The organic layer is separated, washed with sodium hydrogen carbonate solution and dried with anhydrous sodium sulphate. The solvent is evaporated under reduced pressure. The raw product is recrystallized in ethanol to yield 61 g of the product as a white powder having a melting point of 83° C.

EXAMPLE 2 Preparation of Diethyl (2,6-Dichloro-4-fluoro-phenyl)-malonate

Diethyl malonate (0.49 mol) is added to a mixture of sodium hydride (0.51 mol) and 1,4-dioxane (140 ml) at 55 to 60° C. within 2 hours. The mixture is stirred for 10 minutes at 55° C. and copper(I) bromide (0.05 mol) is added. After 15 minutes a mixture of 1-bromo-2,6-dichloro-4-fluoro-benzene (0.25 mol) and 1,4-dioxane (10 ml) is added. The reaction mixture is heated at 100° C. for 15 hours and cooled to 15° C. Hydrochloric acid (12N, 35 ml) is added slowly at 15 to 20° C. The precipitate is filtered off. The filtrate is extracted with diethylether. The organic phase is separated, dried with anhydrous sodium sulphate and filtered. The filtrate is evaporated under reduced pressure to yield 44 g of the product as yellow crystals having a melting point of 170° C.

Diethyl (2-chloro-4,6-difluoro-phenyl)-malonate is obtained analogously.

EXAMPLE 3 Preparation of 5,7-Dihydroxy6-(2,6-dichloro-4-fluoro-phenyl) -[1,2,4]-triazolo[1.5α]pyrimidine

A mixture of 3-amino-1,2,4-triazole (0.15 mol), diethyl (2,6-dichloro-4-fluoro-phenyl)-malonate (0.15 mol, obtained from Example 2) and tributylamine (0.15 mole) is heated with reflux at 180° C. for six hours. The reaction mixture is cooled to 70° C. Aqueous sodium hydroxide (13.6 g/200 ml H₂O) is added and the reaction mixture is stirred for 30 minutes. The organic phase is separated off and the aqueous phase is extracted with diethylether. The aqueous phase is acidified with concentrated hydrochloric acid. A white precipitate is collected by filtration and dried to yield 40.6 g of the product having a melting point of 267° C.

EXAMPLE 4 Preparation of 5,7-Dichloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]-triazolo[1.5α]pyrimidine

A mixture of 5,7-Dihydroxy-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]-triazolo [1.5α]pyrimidine (0.14 mol, obtained from Example 3) and phosphorous oxychloride (110 ml) is heated with reflux at 120° C. for eight hours. Phosphorous oxychloride is partly distilled off. The residue is poured into a mixture of dichloromethane and water. The organic layer is separated, dried with anhydrous sodium sulphate and filtered. The filtrate is concentrated in vacuo and then applied onto a flash chromatography column. The column is consecutively eluted with diethylether/petrol ether (1:2 v/v) to yield 17 g of a yellow powder having a melting point of 149° C. 5,7-Dichloro-(2-chloro-4,6-difluoro-phenyl)-1,2,4-triazolo[1.5α]pyrimidine having a melting point of 124° C. is obtained analogously.

EXAMPLE 5 Preparation of 5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-7-(4-methyl-piperidin-1-yl)-[1,2,4]triazolo[1,5-α]pyrimidine

A mixture of 4-methylpiperidine (3.0 mmoles), triethylamine (3.0 mmoles) and dichloromethane (10 ml) is added to a mixture of 5,7-dichloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]-triazolo[1.5α]pyrimidine (3.0 mmoles) and dichloromethane (30 ml) under stirring. The reaction mixture is stirred 16 hours at room temperature and subsequently washed with 1 N hydrochloric acid. The organic layer is separated, dried with anhydrous sodium sulphate and filtered. The filtrate is evaporated under reduced pressure to yield 1.05 g of a yellow powder having a melting point of 169° C.

EXAMPLES 6-20

The following examples (Table I; structure and melting point) are synthesized analogously to Example 5.

TABLE I

melting Example R¹ R² R⁵ point (° C.)  6 Cyclopentyl H Cl 146  7 2,2,2-trifluoroethyl H Cl 202  8 Ethyl ethyl Cl 142  9 iso-propyl H Cl 182 10 2-butyl H Cl 157 11 norborn-2-yl H Cl 208 12 Cyclopentyl H F 126 13 iso-propyl H F 105 14 Ethyl ethyl F 135 15 2,2,2-trifluoroethyl H F 203 16 1,1,1-trifluoroprop-2-yl H F 220 17 1,1,1-trifluoroprop-2-yl H Cl 18 —(CH₂)₂—CH(CH₃)—(CH₂)₂— H F 19 2-butyl H F 20 norborn-2-yl H F

EXAMPLE 21 Preparation of Diethyl 2,4,6-Trichlorophenylmalonate

Diethyl malonate (6.21 mol) is added to a mixture of sodium hydride (5.13 mol) and 1,4-dioxane (1400 ml) at 55 to 60° C. within 3 hours. The mixture is stirred for 10 minutes at 55° C. and copper(I) bromide (0.5 mol) is added. A mixture of 2,4,6-trichlorobromobenzene (2.50 mol) and 1,4-dioxane (600 ml) is added. The reaction mixture is heated at 100° C. for 14 hours and cooled to 15° C. Hydrochloric acid (12N, 350 ml) is added slowly at 15 to 20° C. The organic phase is separated off and the aqueous phase is extracted with ethyl acetate (250 ml) and toluene (200 ml). The combined organic phases are concentrated in vacuo. The residue is filtered over silica gel, washed with petroleum ether/ethyl acetate (15:1) and the solvent is distilled off. The residue is distilled in vacuo to yield 540 g of the product as a white solid, 144-150° C. at 0.4 mbar.

EXAMPLE 22 Preparation of 5,7-Dichloro-(2,4,6-trichlorophenyl)-1,2,4-triazolo[1.5a]pyrimidine

A mixture of 3-amino-1,2,4-triazole (0.15 mol), diethyl 2,4,6-trichlorophenylmalonate (0.15 mol, obtained from Example 21) and tributylamine (0.15 mole) is heated at 170° C. and ethanol formed during the reaction is distilled off. Subsequently, the reaction mixture is cooled to 130° C. and phosphorous oxychloride (0.45 mol) is added within 30 minutes. The reaction mixture is heated with reflux for 6 hours. A mixture of water and toluene (1.5 l, 6:5) is added slowly. The organic phase is separated, washed with dilute hydrochloric acid and water, dried an concentrated in vacuo to yield a brown viscous oil (45 g) which contains 85% of the title product.

EXAMPLE 23

A mixture of N,N-diethylamine (1.4 mmoles), triethylamine (1.4 mmoles) and dichloromethane (10 ml) is added to a mixture of 5,7-dichloro-(2,4,6-trichlorophenyl)-1,2,4-triazolo[1.5a]pyrimidine (1.4 mmoles) and dichloromethane (30 ml) under stirring. The reaction mixture is stirred 16 hours at room temperature, subsequently washed two times with 1 N hydrochloric acid and once with water. The organic layer is separated, dried with anhydrous sodium sulphate and the solvent is evaporated under reduced pressure. Treatment of the resulting light brown oil with tert.-butyl methyl ether (50 ml) yields beige crystals having a melting point of 199-201° C.

EXAMPLES 24-33

The following examples (Table II; structure and melting point) are synthesized analogously to Example 23.

TABLE II

melting Example R¹ R² point (° C.) 24 2-butyl H oil 25 iso-propyl H oil 26 —CH₂—CH(CH₃)—(CH₂)₃— oil 27 Cyclopentyl H 160 28 —(CH₂)₂—CH(CH₃)—(CH₂)₂— 220 29 norborn-2-yl H 155 30 Cyclopropyl H oil 31 2,2,2-trifluoroethyl H oil 32 2-methylallyl ethyl 33 1,1,1-trifluoroprop-2-yl H

Biological Investigations

Determination of Minimum Inhibitory Concentration by Test Compounds in the Serial Dilution Test

The MIC (Minimum Inhibitory Concentration) value, which indicates the lowest concentration of the active ingredient in the growth medium which causes a total inhibition of myecelial growth, is determined by serial dilution tests using Microtiter plates with 24 or 48 wells per plate. The dilution of the test compounds in the nutrient solution and the distribution to the wells is carried out by a TECAN RSP 5000 Robotic Sample Processor. The following test compound concentrations are used: 0.04, 0.10, 0.20, 0.39, 0.78, 1.56, 3.13, 6.25, 12.50, 25.00, 50.00 00 and 100.00 μg/ml (alternatively a starting concentration of 5.00 ppm with 12 serial dilutions were used). For preparation of the nutrient solution, V8 vegetable juice (333 ml) is mixed with calcium carbonate (4.95 g), centrifuged, the supernatant (200 ml) diluted with water (800 ml) and autoclaved at 121° C. for 30 min.

The respective inocula (Alternaria solani, ALTESO; Botrytis cinerea, BOTRCI; Cochliobulus sativus, COCHSA; Magnaporthe grisea f. sp. oryzae, PYRIOR; Rhizoctonia solani, RHIZSO; are added into the wells as spore suspensions (50 ml; 5×10⁵/ml) or agar slices (6 mm) of an agar culture of the fungus.

After 6-12 days incubation at suitable temperatures (18-25° C.), the MIC values are determined by visual inspection of the plates (Table III and IV).

TABLE III Ex. No. ALTESO BOTRCI COCHSA PYRIOR RHISZO 5 0.39 0.39 0.78 0.04 12.5 6 0.78 3.13 25 0.1 50 7 3.13 6.25 >100 0.1 25 8 0.78 0.78 >100 0.04 0.78 9 12.5 12.5 >100 0.78 25

TABLE IV Example No. PYRIOR 23 0.10 24 1.56 25 0.39 26 0.10 27 0.20 28 0.10 29 0.39 30 1.56 31 0.04 

What is claimed is:
 1. A compound of the formula I

in which R¹ and R² each independently represent a hydrogen atom or an optionally substituted alkyl, alkenyl, alkynyl, alkadienyl, haloalkyl, aryl, heteroaryl, cycloalkyl, bicycloalkyl or heterocyclyl group, or R¹ and R² together with the interjacent nitrogen atom represent an optionally substituted heterocyclic ring; R³, R⁴ and R⁵ each independently represent a fluorine or a chlorine atom, provided that at least one of R³, R⁴ and R⁵ is a chlorine atom; and X represents a halogen atom.
 2. A compound according to claim 1 in which R¹ represents a straight chained or branched C₁-C₆-alkyl, C₁-C₆-haloalkyl, or C₂-C₆-alkenyl, or a C₃-C₆ cycloalkyl, or C₅-C₉ bicycloalkyl, and R² represents hydrogen or C₁-C₆-alkyl, or R¹ and R² together with the interjacent nitrogen atom represent a heterocyclic ring having 5 or 6 carbon atoms, optionally substituted by one or two C₁-C₆-alkyl groups.
 3. A compound according to claim 1 in which R² represents a hydrogen atom.
 4. A compound according to claim 1 in which one of R³, R⁴ and R⁵ is a fluorine atom and the other two are chlorine atoms.
 5. A compound according to claim 4 in which R³ and R⁵ present chlorine atoms.
 6. A compound according to claim 1 in which R³ represents a chlorine atom, and R⁴ and R⁵ represent fluorine atoms.
 7. A compound according to claim 1 selected from the group consisting of: [5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-cyclopentyl-amine; [5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-7-(4-methyl-piperidin-1-yl)-[1,2,4]triazolo[1,5-α]pyrimidine; [5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5<]pyrimidin-7-yl]-(2,2,2-trifluoro-ethyl)-amine; [5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-(1,1,1-trifluoro-prop-2-yl)-amine; [5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-diethyl-amine; [5-Chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-isopropyl-amine; sec-butyl-[5-chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-amine; bicyclo[2.2.1]hept-2-yl-[5-chloro-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-amine; [5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-cyclopentyl-amine; [5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-7-(4-methyl-piperidin-1-yl)-1,2,4]triazolo[1,5-α]pyrimidine; [5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-(2,2,2-trifluoro-ethyl)-amine; [5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-(1,1,1-trifluoroprop-2-yl)-amine; [5-Chloro-6(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-diethyl-amine; [5-Chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-isopropyl-amine; sec-butyl-[5-chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-amine; bicyclo[2.2.1]hept-2-yl-[5-chloro-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidin-7-yl]-amine; but-²-yl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amine; isopropyl-15-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amine; [5-chloro-6-(2,4,6-trichlorophenyl)-7-(3-methyl-piperidin-1-yl)-1,2,4]triazolo[1,5-α]pyrimidine; cyclopentyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]-pyrimidin-7yl]-amine; 5-chloro-6-(2,4,6-trichloro-phenyl)-7-(4-methyl-piperidin-1-yl)-1,2,4]triazolo[1,5-α]pyrimidine; diethyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amine; norborn-2-yl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]-pyrimidin-7-yl]amine; cyclopropyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]-pyrimidin-7-yl]-amine; 2,2,2-trifluoroethyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]-pyrimidin-7-yl]-amine; N-ethyl-N-2-methylallyl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amine; and 1,1,1-trifluoroprop-2-yl-[5-chloro-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-a]pyrimidin-7-yl]-amino.
 8. A process for the preparation of a compound of formula I as defined in claim 1 which comprises reacting a compound of formula II

in which R³, R⁴, R⁵ and X are as defined in claim 1, with an amine of formula III

in which R¹ and R² are as defined in claim
 1. 9. A compound of formula II

in which R³, R⁴, R⁵ and X are as defined in claim
 1. 10. A compound selected from 5,7-dihydroxy-6-(2,4,6-trichlorophenyl)-[1,2,4]triazolo[1,5-α]pyrimidine, 5,7-dihydroxy-6-(2,6-dichloro-4-fluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidine and 5,7-dihydroxy-6-(2-chloro-4,6-difluoro-phenyl)-[1,2,4]triazolo[1,5-α]pyrimidine.
 11. A fungicidal composition which comprises a carrier, and as active agent, at least one compound of formula I as defined in claim
 1. 12. A method of combating fungus at a locus which comprises treating the locus with a compound of formula I as defined in claim
 1. 13. A method according to claim 12 wherein said fungus is Pyricularia oryzae f. sp. grisea. 